Robert c



R. C. MATHES.

VACUUM TUBE REPEATER.

APPLICATION FILED DEC-21,1918.

1,318,4G8. Patented Aug 19, 1919.

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"f UNITED STATES PATENT OFFICE.

'ROBEBT C. MATHES, OE NEW YORK, Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

VACUUM-TUBE nnraamn.

To all whom it may concern.

Be itknown that I, ROBERT C. MATHES, a citizen of the-United States, residing at .New York, in the county of Bronx, State of 5 New York, have invented certain newand useful Improvements. in. Vacuum-Tube Repeaters, of which the following is 'a' full, clear, concise, and exact description.

This invention relates to vacuum tube repeatersand is in the nature of an imrovement on the type of repeater shown in nited States patent to E. H. Col-pitts, No. 1,128,292, dated'February 16, 1915. I g In this type of repeater, means are provided for producing two thermlonic or space currents either in a single evacuated tube or in separate tubes, and a control electrode,-fu sually in the form of-a,'grid is provided for each repeater current -'if'ofr'supplying thereto the electric impulses which are to be repeated. These control electrodes have heretofore been connected to opposite ends of -the secondary. of" a. transformer through the primary -of which the'electric impulses are passed. T-he'mid-point 'of the secondary was connectedto the cathode or Y cathodes which serve as the source or sources ofthe thermionic currents. By reason of this arrangement,- each impulse is impressed on both control electrodes but in such' a manner that one of them is at a. negative potentialwhen-the other is at a positive potential and vice versa, and the received current is transmitted with less distortion than if it were passed through a single thermionic device. As heretofore designed, the input transformer elements have all been inductively related to each other,-and while repeaters so designed operate satisfactorily,

there is some loss in efiiciency due to the fact that there isa flow of current from the grid which is momentarily positive to thefcorresponding'cathode, and for this reason a loss in potentialdrop across all of the parts of the transformer. This flow of curre'ht depends on'the potential of the impulse to be transmitted and is therefore variable, with a corresponding distortion of the signal.

It is the objectof this invention to provide a method and means for maintaining the potential of the grid or control electrode which is momentarily negative at a relatively high value, thus compensating for the which isv positive.

Specification of Letters Patent.

lowered potential of the control electrode Patented Aug. 19, 1919.

Application filed December 27, 1918. Serial No. 268,458.

This object is attained inthe form of the invention shown herein, by coupling the control electrodes to the source-of received impulses by means of two separate transformers non-inductively related to each other.

This and other objects of this invention will appear more fullyfrom the following detailed description and appended claims taken inconnection with the accompanying drawings in which Fig. 1 represents a repeater circuit embodying the invention in which separate tubes areused for'the two branches, and

Fig. 2 represents a modification inwhich all of t-he electrodes are placed in a single secondaries of the respective input trans-' formers 21 and 22, the primaries of which are in series in the line or circuit 23 which is connected toa source (not shown) of electric impulses, such as a telephonic current to be transmitted.

In the operation of this circuit arrange ment, as. soon ,as'the cathodes 12 and 13 are heated to such a temperature that they will emit electrons, at thermionic 'or space current is caused to flow between each cathode and its corresponding anode because'of the potential diflerence established by the source of current 20. Variations in these currents are produced by the action of grids 14 and 15 in the following manner. I

For convenience and to harmonize with the direction of thermionic currents stated above, electric currents will be regarded as flowing from negative to positive. When an impulse. passes through the primaries 01 the'input transformers 21 and 22 in the di rection of the arrows, at current is induced in the secondariesin the o posite direction, the potential of grid 14- ecomes positive with respect to cathode 12, and the potential of grid 15 becomes negative withrespect to cathode 13. Since current flows from cathode 12 to grid 14 when the latter is positive, there is a lowering in the potential of the grid and an increase in the current flow-' ing in the rimaries of both input transformers. T is results in a high negative potential at grid ,15, since the impedance of the tube is very high to the flow of negative electricity toward the cathode. During the reverse half of the cycle of the incoming impulse, conditions are just reversed, a high negative potential being maintained at grid 14. As is well known the thermionic current between cathode and anode is decreased by a negative potential on the grid and increased by a positive potential thereon. Hence although current is flowing in opposite directions in the two halves of the primary of output transformer 19, variations therein are in the same direction, and such variations are confined in the secondary as amplified impulses having substantially the same wave form as that of the received impulses.

The arrangement and operation of the form shown in Fig. 2 is essentially the same I as that ofFig. 1. It difiers in that a single tube 24 instead of two tubes is used, thus permitting the omission of one electrode. As shown, one of the cathodes is omitted and a single cathode 25 serves to suppl electrons for both thermionic currents. therwise, the connections 'and manner of operation are the same in both arrangements.

While two embodiments of the invention have been shown and described, obviously the invention is applicable ,to other arrangements and it is to be understood that it is not except; as by the following claims.

What is claimed is:

1. The combination of an incoming line,

an outgoing line, a thermionic repeater therebetween having divided input circuits, and a plurality ofi non-inductively related transformersconnecting said incoming line to said divided in ut circuits.

.2. A vacuum tu repeater having means for producing two thermionic currents, ,con-

. trol means for each of said currents, means for impressing electric impulses on said control means in. such a manner that one control means is negative" when the other is P v the potemal of the control means wh ch 1s iveand vice versa, means insuring that negative is greater than that of the control means which is positive, and means for combining and transmitting the variations thus produced in said thermionic currents.

3. The method of operating a vacuum tube repeater having two space current circuits and a control electrode for each of said circuits, which comprises impressing received electric impulses on said control elecis negative when the other is positive and vice versa and keeping the potential of the electrode which is'negative greater than the potential of the electrode which is positive.

4. A vacuum tube repeater having a; divided input circuit, a divided output circuit,

means for producing thermionic currents in the branches of said output circuit, control electrodes in the branches of said input circuit adapted to control said thermionic currents, and a circuit for electric impulses to be received having separated inductive couplings with the branches of said input circuit.

5. A vacuum tube repeater comprising trodes in such a manner that one of them two vacuum tubes each having a cathode,

an anode and a control electrode, a source of space current in circuit with said cathodes other end connected through two branches to said anodes, an output line inductively related to said branches, at line adapted to conduct electric impulses, and two input trans-- :Eormershavin their primaries 1n series 1nsaid last mentioned line, the secondaries of sald transformers having their adjacent ends connected to said'heating current circuit and their opposite ends connected to said control electrodes respectively.

witness whereof, I hereunto subscribe my name this 24th day of Dece her A. D.

191s. a j

ROBERT c. MATBZES. 

